1. Field of the Invention
The present invention concerns conbinations of zinc compounds furnishing zinc ions and one or more enzymes which may be a protease, a carbohydrase, or a lipase, or mixtures thereof.
Dental plaque forms as a deposit on and around teeth. It is a product of microbial growth, a dense microbial layer consisting of a mass of microorganisms embedded in a matrix, which accumulates on the tooth and adjacent surfaces. It has been reported that the microorganisms immediately after dental prophylaxis are mainly coccoidal organisms, which, in the mouths of some persons at least, change to filamentous organisms after a few days.
A wide variety of microorganisms are found in the oral cavity, some of which can produce acids or toxic materials. In addition to these microorganisms, dental plaque is composed of many other substances, such as mucoproteins and minerals derived from saliva, dead cells, and food residues which are dissolved, or present in particulate form. A major binding force holding plaque together is a matrix formed of the aforementioned mucoprotein or sticky polysaccharide substances secreted by some types of microorganisms.
Plaque deposition varies in extent throughout the oral cavity. Larger amounts tend to accumulate on those less accessible and more sheltered areas of teeth which cannot readily be reached with a toothbrush; rinsing with water alone usually will not dislodge such plaque. Plaque may also develop in pits and fissures of the teeth. It is extremely difficult to remove such plaque by mechanical means. With growth and multiplication of the bacteria, the plaque increases in size and becomes more viscous and thicker. The situation is exacerbated by the production by some microorganisms of a polysaccharide slime.
Recent dental research points to the fact that the major potential for harm by plaque resides in the bacterial component thereof. Bacterial metabolism can result in the production of acids, toxins and enzymes which are deleterious to the neighboring oral tissues. These materials can be retained in the mucoprotein matrix of the plaque and thus exert a direct influence on the adjacent tooth structures and gingivae. There is evidence pointing to plaque as being a direct cause of caries due to the generation of acids within its structure. Also, a direct correlation has been observed between the presence of dental plaque and the occurrence of gingivitis.
Dental calculus is a calcified or calcifying mass which is generated from dental plaque. In its more advanced state, it consists of an organic matrix, representing about 20% of the deposit and containing carbohydrates, proteins, bacteria, cellular debris, and other organic materials. The major portion of calculus is inorganic. This portion contains calcium, phosphorus, magnesium and lesser amounts of other mineral elements. The calcium and phosphorus are present primarily in the form of various calcium phosphate species, the most common of which is hydroxyapatite.
There are at least two well-recognized stages in calculus formation. First, the organic matrix or mucilaginous plaque (individually or simultaneously) deposits upon the tooth enamel or cementum, and may spread to adjacent areas in the oral cavity. At this stage, vigorous oral hygiene, especially tooth brushing, can remove much of the deposit and effectively reduce the amount of calculus subsequently found. In the second stage, alterations occur within the plaque which initiate mineralization. The exact mechanism whereby mineralization occurs has not yet been determined. Plaque tends to accumulate, selectively, calcium and phosphate. In one theory, it has been suggested that it is the activity of the microorganisms within the plaque which leads directly to the formation of dental calculus. Of the various types of bacteria present, the Leptothrix and Actinomyces appear to have been implicated most directly as being involved in both intercellular and extracellular mineralization. In another theory, it has been proposed that under appropriate conditions the mucilaginous matrix of the dental plaque is so altered as to promote mineralization. Here, too, the role of bacteria appears to be important; it has been observed that mineralization can start near the bacteria and that the bacteria are able to manufacture materials which are able to initiate the formation of insoluble calcium salts.
The clinical importance of plaque and calculus has been demonstrated many times over and an association between calculus and the occurrence of periodontal disease has long been observed. Removal of calculus is one of the most commonly practiced preventive measures against periodontal disease. As mentioned above, recent findings point toward plaque being involved in both carious lesion formation and in the initiation of periodontal disease even in the absence of calculus development. Thus, a direct correlation has been made between the appearance of plaque and gingivitis even in the absence of calculus.